Vacuum tube circuits



Jan. 25, 1.927. l;6 15,808

M. LATOUR VACUUM TUBE CIRCUITS Filed Aug. 19, 1921 @nvm/woz MARxus LAouR Patented" Jn. 25, 1 927.

UNITED ,STATES PATiazN'rA OFFICE.

MARIU'S LATOUR, PARIS, FRANCE, ASSIGNOR T0 T A'I'OUIIR' CORPORATION, 4OIF JER- SEY CITY, NEW JERSEY, A CORPORATION F DELAWARE. Y

VACUUM TUBE cmcurrs.

'Application filed August 19, 1921, Serial No. 493,675, and in France March 5. 1919.

It may often'be desirable to supply current Ato the filament circuits of three-electrode tubes, constituting an amplifying system, through existing commercial power circuits.

5 y ln view of the fact that the voltage of .such

power circuits is usually much higher than de-A sirable for filament circuits of vacuum tubes,

it would be'nccessary to connect aresistance A in series with the filaments. However, it is well known that the heating of the filaments I nust be done at a strictly constant voltage. Fonfthisreasom the filaments can not satis- Jr'actorily be fed directly from an existing direct currentpower circuit by using lmerely 'i 15 an ohmic resistance inserted in series with the filaments, because the slightestvoltage fiuctuations would affect the heating and would cause noises in the receivers of the amplifying apparatus. i y Instead of' he resistance, an inductance coil may be placed in 'series with the filaments in the heating circuit. However, if

this inductance coil must absorb the continuously high voltage the consumption o'f which was, in accordance with the first suggestion', the function of the resistance, itwill be seen that the inductance of this coil assurnes a value entirely too large to be practical. This is .due to the fact that the' inductive reactance of the coil must be larger than the resistance of the winding thereof'if anonfluctuating current isto besupplled to the filaments from the fluctuating direct current source. v

Even if a resistance unit is placed in series with the inductance coil instead of following the arrangement just described, the size of the inductance coil must still be so great, in order to maintain the-large r-eactancevresist- 4o ance ratio necessary for anon-fiuctuatingA current, that it is uncommercial.

It is the object lof the present invention to 'provide a current feeding arrangement in which the size of this inductance coil is rea duced -to al practical value'.- This is accomplished by connecting a resistance unit and an inductance coil in series with the filament or filaments across the power leads and by connecting a resistance .in shunt of the inductance and of the filamentv or filaments.-

l. The single figure of thekaccompanying drawing represents one embodiment of a cir- 'the resistance 'unit 7 may be variable in the cuit arrangement arranged in accordance with this invention.

The tube 1 comprises the well-known parts: the filament, 2, the grid 3 and the plate 4. The filament 2 is -fed from'. the power source v5 through a resistance 6 and an` inductance 8, and it is shunted by a, resistance 7. The resistance 6 is sufficiently 'large so that the voltage from the power-source is reduced to the4 proper value for heating the filalnent of the tube, and the value of the resistancc 7' is small with respect to the reactance value of inductance coil 8. By this arrangement the size of the inductance coil 8. is determined, not by the size of the resistance l6 but by that of the resistance 7 Furthermore, it will be understoodthat form of a rheostat to control the supply of heating current to the filament. Having described my invention what I claim is: 7 1. In combination with a thermionic tube having a filament, a source` of direct current for heating said filament, said current source being of substantially higher voltage than necessary for heating said filament and having disturbing fluctuations in voltage, a

. .80 series circuit connected across `said source of direct current, said series circuit including a resist-ance unit, an inductance unit and said filament, and aresistanceunit connected in shunt of said filament and of said inductance 35 unit whereby fluctuations in the current of l said filament are reduced.

2. Inf combination .with a thermionic tube having a filament, a source of' direct current for heating said-filament, said current'source 90 Abeing of substantiallyhighervoltage than necessary for heating said filament and having disturbing fiuctuations in vltage, a ,ser ries circuit'fc'onnected tov said current source, said series circuit including a resistance, an U5 inductance and at least one filament, and a second resistance connected in `shunt of said inductance andof said filament, said second resistance being small in value with' respect to the reactance of said inductance, whereby fiuctuations in the current of saidl filament are reduced.

MARIUS LATOUR. 

